April 3, 2023

What kind of burrs are used in hand grinders?


Although many people use electric grinders, hand (or manual) coffee grinders are still incredibly popular among both coffee professionals and consumers.

This is mostly because the quality of hand grinders has evolved significantly over the years. And this is especially apparent when it comes to the design of the burrs, as well as the materials used.

The type of burrs used in hand grinders has a significant impact on the quality of extraction, and therefore the flavours.

To find out more about hand coffee grinder burrs, I spoke to Giulia Bagato, Marketing Manager at Fiorenzato. Read on for some more insight.

You may also like our article on which material your grinder burrs should be made from.

A look at the burrs inside a hand coffee grinder.

How have hand grinders changed over the years?

It’s fair to say that manual coffee grinders have come a long way since they were first invented.

Prior to the 1600s, one of the most common ways to grind coffee beans was by using a pestle and mortar. However, this method was time consuming and impractical. As a result, more and more people started to use spice grinders so they could grind their coffee to a finer grind size in a shorter amount of time.

However, in the late 17th century, English inventor Nicholas Book is believed to be the first person to invent the hand grinder as we know it today. 

Essentially, coffee beans were placed into a grinding chamber, which sat atop a wooden box. By turning a crank lever on top of the grinding chamber, the beans were ground coffee and then dispensed into a wooden drawer.

Book’s grinder quickly became a success, which led other companies to develop similar models – most notably French car manufacturer Peugeot, which still makes manual coffee grinders today.

However, Giulia explains that as more coffee consumers started to focus on convenience in the 19th and 20th centuries, hand grinders began to wane in popularity.

“Manual coffee grinders date back centuries to when grinding coffee at home was a common habit,” she says. “This practice gradually began to disappear as people increasingly preferred to buy pre-ground coffee.”

Specialty coffee & hand grinders

However, over the past couple of decades, specialty coffee has grown more and more popular. With this movement comes an increasing focus on the craft and skill of making coffee, as well as a preference for freshly roasted and brewed coffee.

In line with this, there have been more and more premium hand grinders available on the market. 

“Modern manual coffee grinders are completely different from those used in previous centuries,” Giulia says. “They have more precise mechanical designs, as well as being more compact and manageable.”

A look at the Pietro hand coffee grinder burrs.

Common types of burrs

Depending on manufacturer specifications, it’s common for electric grinders to use either conical or flat burrs. However, by default, most hand grinders include conical burrs.

There are some notable differences these two types of burrs:

  • Conical burrs: one cone-shaped burr sits inside the other, which is ring-shaped. This means the coffee is ground vertically, and gravity plays a key role
  • Flat burrs: two ring-shaped burrs sit on top of each other. The distance between the burrs is what determines the grind size, so grinding happens horizontally

The shape of burrs has significant influence over grind size, as well as particle size distribution. Conical burrs result in bimodal particle size distribution, which essentially means that they produce more of both smaller and larger-sized particles.

Conversely, flat burrs result in unimodal particle size distribution, and thereby produce more evenly sized ground coffee particles. Ultimately, this makes for a more even extraction, and can also result in more experimentation with grind size and its effect on flavour.

Materials used for hand grinder burrs

Traditionally, burrs in hand grinders are made from either:

  • Ceramic
  • Plastic
  • Steel

The first two materials are most often used for lower price-point hand grinders. While these grinders are certainly more affordable, ceramic and plastic burrs tend to lose their sharpness much more quickly than other materials like steel. When burrs start to dull, grind size distribution and therefore extraction can be affected.

Moreover, ceramic burrs in particular are also fragile, and are therefore more prone to breaking than other materials.

Stainless steel burrs are more commonly found in higher-end hand grinders, and retain their sharpness for longer. They also produce much more consistent results.

However, steel burrs are prone to retaining more heat than plastic or ceramic, which can adversely affect extraction. In order to minimise heat retention as much as possible, grinder manufacturers will often use different grades of steel. 

For instance, Fiorenzato’s Pietro manual coffee grinder has Bohler M340 steel flat burrs with a Dark-T® coating so that they have a lower friction rate and retain less heat. This means fewer flavour and aroma compounds are lost when grinding coffee.

The exterior of a Fiorenzato Pietro hand coffee grinder.

How have hand grinder burrs developed in recent years?

With more and more people interested in making café-quality beverages at home, demand for higher-quality hand grinders has increased in recent years.

“Manual grinders are undoubtedly one of the most straightforward and affordable pieces of equipment for making excellent coffee at home,” Giulia tells me.

Alongside better quality design and build, the type of burrs in hand coffee grinders has also changed over the past few years.

One example is Fiorenzato’s Pietro manual grinder, which includes vertically-aligned steel flat burrs.

“The challenge Fiorenzato had to overcome was creating a hand grinder with more innovative features,” Giulia explains. “We then designed a manual grinder with vertically-aligned flat burrs as most other brands include conical burrs.

“We then experimented to find burr geometries that would work at a lower number of rotations per minute,” she adds. “This means the Pietro grinder is more ergonomically designed as it is easier to grind coffee.”

Grinding for filter & espresso

Giulia explains that the Pietro manual grinder is available in two models: the MultiPurpose grinder with the B-Modal burr set and the ProBrewing grinder with the M-Modal burr set.

“The B-Modal burrs result in a bi-modal particle size distribution curve, which allows you to grind for both espresso and filter,” she says. “This type of burr is particularly suitable for people who want to experiment with different recipes, as well as those who prefer coffee with more mouthfeel and body.”

The M-Modal burrs, meanwhile, are designed to deliver the optimal grind size distribution for the user’s required brewing method. This is because they produce very few fines and boulders (larger-sized particles) and extraction becomes more even. 

“This type of burr set is more suited to grinding for filter coffee, as well as for those who want a cleaner-tasting and more defined cup of coffee,” Giulia tells me.

“A numbered stepless grind adjustment ring sets the distance between the two burrs,” she adds. “The 60g-capacity hopper connects directly to the grinding chamber, and the ground coffee is then stored in a magnetically-sealed container, which helps to preserve its aromas and flavours.”

An example of a blue Fiorenzato Pietro hand coffee grinder.

Tips and advice for using premium hand grinders

One of the most important factors to consider is how to adjust your grind size when switching between different brewing methods. This means first figuring out how you adjust the grind size on your grinder itself.

Most traditional hand grinders have either a ring or dial adjustment system. Ring adjusters are usually found at the top of the grinder, while dial adjusters are located underneath the burr set. 

The process of adjusting grind size varies between manual grinders, but many require you to attach the handle before making any changes to the ring or dial adjusters.

For grinders with a stepless adjustment system, like the Pietro, changing the grind size is more straightforward – especially when switching between different brewing methods.

Cleaning and maintenance

Another important tip that Giulia shares is to keep your manual grinder clean and well maintained.

“With Fiorenzato’s Pietro grinder, it’s easy to quickly access the grinding chamber,” she explains. “You just press a button and pull out the grinding chamber using the lever and the fixed burr.”

To effectively clean your manual grinder, Giulia recommends using a dry brush and cloth to remove any old, stale grounds, as well as any oil buildup, from the grinding chamber and burrs.

The exterior of a Fiorenzato Pietro hand coffee grinder.

If you’re looking to brew excellent coffee, it’s impossible to overstate the importance of a high-quality grinder. And when you’re looking for a premium hand grinder in particular, burr quality is a great indication of overall performance.

Ultimately, investing in a hand grinder which results in more even particle distribution will only serve to improve the quality of your coffee.

Enjoyed this? Then read our article on how to clean and maintain your coffee grinder.

Photo credits: Pietro Grinders

Perfect Daily Grind

Please note: Fiorenzato is a sponsor of Perfect Daily Grind.

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